1. Field of the Invention
The present invention relates generally to medical methods, apparatus, and kits. More particularly, the present invention relates to methods, systems, and kits for percutaneously delivering implantable articles, such as subcutaneous drug inserts, to solid tissue locations.
Implantable articles are useful for a wide variety of medical purposes. Of particular interest to the present invention, drug inserts and controlled release reservoirs may be subcutaneously implanted in order to release a drug or other biologically active substance over time. Usually, the insert or reservoir will be implanted intramuscularly or intraperitoneally by first forming an incision which permits the article to be implanted at the target site. Often, a large bore needle or cannula is used to inject the insert or reservoir to the target location. Such devices, however, often result in coring of the tissue, and subsequent injection of the drug insert pushes against such cored tissue, rendering placement difficult. While such problems have been at least partly overcome by the use of trocar/cannula assemblies where the trocar cuts through tissue, the use of relatively large diameter trocars is traumatic to the patient and can leave scarring.
An improvement over the use of large diameter needles and trocars is proposed in U.S. Pat. No. 5,304,119. The '119 patent teaches use of a tapered cannula having a pair of opposed tines overs its distal end. The tines meet together in a "duck bill" fashion and may be advanced through solid tissue with reduced trauma to the patient. After initial placement of the cannula, a drug insert may be advanced axially through the device, forcing the opposed tines to open and permitting placement of the insert at the desired target location. While workable and an improvement over prior delivery systems, reliance on passage of the drug insert to open the opposed tines can be problematic. In particular, the mechanical action can physically damage the drug insert prior to its delivery to the tissue target site.
For these reasons, it would be desirable to provide improved methods, systems, and kits for delivering implantable articles, such as drug inserts and controlled release reservoirs, to solid tissue locations. In particular, it would be desirable to provide for percutaneous delivery of such articles in a manner which is both minimally traumatic to the patient and minimally damaging to the article. At least some these objectives will be met by the invention described hereinafter.
2. Description of the Background Art A device and method for injecting implants are described in U.S. Pat. No. 5,304,119, discussed in more detail above. Radially expanding dilators of a type suitable for use in the methods of the present invention are described in U.S. Pat. Nos. 5,183,464 and 5,431,676, and are commercially available under the tradename STEP.TM. from InnerDyne, Inc., Sunnyvale, Calif., assignee of the present application. Other pertinent patents include U.S. Pat. Nos. 5,674,240; 5,484,403; 5,403,278; 5,201,756; 4,899,729; 4,716,901; and 3,788,318.